A generic gear unit with a disc-shaped drive element and an output element in the form of a tooth segment is known from DE 10 2007 059 712.8. The output element is made to be turnable about an axis of rotation. The tooth segment is in an effective connection with a barrier member of a steering-wheel lock of a motor vehicle. The drive element is thus driven by a screw gear. Further, the gear unit can be transferred to a neutral state in which the tooth segment is uncoupled from the disc-shaped drive element. In this neutral state a spring element exerts a defined force on the tooth segment by which the tooth segment is pressed back in the direction of the drive element.
With a continuing turning motion of the drive element an undesirable sound can result in which the tooth structure of the tooth segment periodically bumps into the tooth structure of the drive element. There is a further drawback that, in a change from the uncoupled state to the engagement state, there is no guarantee that the respective tooth structures will catch into each other in the proper position. The consequence of this is that the respective tooth tips of the tooth structures of the drive element and the output element can reach each other so that the gear unit jams. This can result in damage to the gear unit, thereby interrupting the movement of the drive element on the output element.